Method and apparatus for electrolytic treatment of slide fasteners



C. C. COHN METHOD AND APP TUS FOR ELECTROLYTIC TREATME SL FASTENERS F'i Oct. 1952 INVENTOR. CHARLES 0. (JOHN ATTORNEYS IVIETHOD AND APPARATUS FOR ELECTROLYTIC TREATIVIEN T F SLIDE FASTENERS This invention relates to methods and apparatus for the electrolytic treatment of elements of slide fasteners of the zipper type, the treatment referred to including electroplating, anodizing of aluminum elements, or the like. The invention has particular reference to the electrolytic treatment of slide fasteners in closed form and in long strips, the treatment being of a continuous nature.

From the following description, it will be evident that the invention is applicable to the electrolytic treatment of such fasteners in general, but to simplify the description, stress will be particularly laid on the anodizing of aluminum or aluminum alloy elements, the handling of the elements evidently being applicable to treatment such as electroplating.

For many uses, particularly in clothing, the natural color of the metal from which the zipper elements are formed is objectionable, and, consequently, it has been generally customary to provide covering flaps for zippers to hide the elements from view. These flaps, however, are not always desirable and in many instances a better appearance of the product would result if the zipper elements, though exposed to view, were colored either to match the adjacent fabric or to contrast with it to provide ornamentation. Various methods of coloring or attempting to color elements have been used. For example, the exposed portions of zipper elements have been painted. When a garment having painted zippers is sold the appearance may be quite attractive; but in use the paint very readily becomes dislodged and the irregular exposure of bare metal detracts greatly from the appearance of the garment. It has been recognized that a quite superior colored surface from the standpoint of resistance to wear could be produced if zipper elements were made of aluminum or its alloys and the exposed surfaces were oxide coated and then dyed. In particular, if this oxide coating was formed by anodizing the colored oxide coating, being extremely hard, would be quite resistant to wear.

While the desirability of providing colored aluminum zippers of the type just mentioned has been recognized, serious difiiculties are involved in securing these results in an inexpensive and commercially feasible fashion. Desirably, commercial production should involve the handling of continuous strips of closed zippers, i. e. zippers comprising the interengaged elements secured to fabric tapes. The process should furthermore be completely consistent with the use of standard zipper-forming machines and should involve no material change in the form of the zipper elements.

In the case of a closed zipper, it might appear that all of the zipper elements are in series contact and that, consequently, it would be possible to secure electrical connection with all of the elements by connection with an electrical current source at one end of the strip. In fact, however, this is not the case at least to the extent of providing sufiiciently good electrical contact to insure the proper carrying of current with substantially negligible resistance through any considerable length of the strips. In particular, anodizing of aluminum zipper elements re- Patented Aug. 9, 1955 quires relatively heavy currents and the resistance, due to poor contracts, would cause a very rapid falling oif of voltage along the zipper. In accordance with my Patent No. 2,572,838, dated October 30, 1951, there is provided a method for the electrolytic treatment of zippers involving the securing of good electrical contacts between the elements of a closed zipper by imparting a sinuous form thereto which insures tight electrical engagement at the projections and sockets of the zipper elements. The method disclosed in said patent is, however, adaptable only to the anodizing or other electrolytic treatment of finite lengths of zippers inasmuch as the sinuous configuration can be achieved satisfactorily only through racking.

Various other methods for the anodizing or other electrolytic treatment of zippers have been proposed but these generally involve special zipper constructions or the use of special apparatus for forming or handling the zipper elements. In my Patent No. 2,596,888, dated May 13, 1952, there is disclosed a method involving the preliminary treatment of a shaped wire from which the zipper elements are formed. It is, however, from the standpoint of simplicity of production, desirable to effect the electrolytic treatment on a finished closed zipper and, in particular, this is desirable when the zipper elements and the carrying tape are to be given the same color.

This is possible in the case of anodized aluminum zipper elements, when the completed closed zipper may be subjected to dyeing which will color not only the anodized coatings of the elements but the carrying tapes as well.

In my applications Serial Nos. 301,509 and 301,510, filed July 29, 1952, there are disclosed various methods and apparatus for the continuous anodizing or other electrolytic treatment of zippers. Reference may be made to these applications for discussions of particular characteristics of zippers and the problems involved. The present invention relates to still other methods and apparatus for the electrolytic treatment of zippers, and as will become apparent, the methods and apparatus involved are applicable to both the continuous treatment of zippers or to the treatment of relatively short lengths thereof in batch fashion.

The general object of the present invention, therefore, is to provide a method and apparatus for the electrolytic treatment of closed zippers which, in the case of anodizing of aluminum zipper elements may be followed by dyeing. In accordance with the invention, and without detriment to the zippers, good electrical contacts between the zipper elements are secured resulting in the possibility of handling closed zippers continuously in substantially the same fashion as one might handle a wire in electrolytic treatment thereof. This general object of the invention and more detailed objects thereof will become apparent from the following description read in conjunction with the accompanying drawing in which:

Figure l is a diagrammatic plan view, fragmentary in nature, showing the association of a pair of closed zippers in a fashion suitable for carrying out the improved method;

Figure 2 is a fragmentary section taken on the plane indicated at 22 in Figure 1;

Figure 3 is a transverse section taken on the plane indicated at 3-3 in Figure 1; and

Figure 4 is a diagrammatic section showing the apparatus suitable for carrying out a continuous electrolytic procedure.

As pointed out particularly in the copending applications referred to above, a closed zipper does not ordinarily provide good electrical continuity between the zipper elements. Zipper elements as ordinarily manufactured are not made to close tolerances as will be evident upon microscopic examination with the result 3 that electrical contacts'occur'only in random fashion between the elements of a closed zipper. As is pointed out, particularly in my application Serial No. 301,510, good electrical contact may be proyided iftheizipper tapesgare pulledapart or caused to'provide a'tiltingjof the zipper elements about the longitudinal axis ot the p e It has been found that good electrical continuity may be secured if a pair of closed zippers are intermeshed in the sense that the elements of one zipper are located in the :spaces between the elements of another zipper. In a closed zipper it will be found that the'spacing between adjacent elements secured to one tape is necessarily g'r'eater than the width measured along the tapes of any element. I Iowever, when the'tapes are superimposedso that their elements mesh, even though the elements of one tape dojnot engage the elements of the other tapefwith which they are interspersed, the mutual assembly provides good and reliable electrical continuity suificing rm: the carrying of such relatively heavycurrejntsas are involved in anodizing ofaluminum eitments.'nven disregarding, preliminarily, improved interelement contacts resulting from the relative bending of the Zipper elements with respect toeach other about the longitudinal axes of the tapes, the association of two closed zippers in intermeshing fashion 'will obviously greatly lessen the frequency of breaks in electrical continuity which are present in the case of a single tape. in other 'words, electrical discontinuity which may occur between the adjacent elements of one tape is very likely to be bridged by good electrical continuity between elements of the other tape. When this condition is combined with relative angular position of the elements about the "axes'of the tapes, highly reliable electrical continuity is secured making it'unnecessary to provide more or less continuous electrical contact with the elements, it becoming sufficient to provide contact only Where the'asser'nbly of zippers enters a tank, in a continuous process,'or'only atone point of a'pair or assembled zippers when a batch type of treatment is involved. In particular, the new 'method is advantageous in that a pair of zippers may be handledas a unit, thus increasing the electrolytic capacity of a given tank. Furthermore, as will become apparent, there is provided free escape of gas, the a'c'cumulation of which might interrupt the flow of current between the eleni'en'ts and the electrolyte thus preventing satisfactory electrolytic action. 7 v

Referring'first to Figures 1, 2 and}, there is illustrated therein'the association of a pair 'of'closed zipr pers in what is herein referred to as intermeshihg fashion. An upper'zipper, viewing Figure l, comprises the fabric tapes 2and 4 beaded at their adjacent edgesin conventional fashion tosupportthe respective elements 6 and 8 which in the closed zipper are interlocked with each other. A lower closed zipper is illustrated as comprising the tapes lii'a'nd 12 carrying the zipper: elements 14 and 16, respectively, which are also'inter engaged. The projections 18 and the'sockets 2d of thezipper elements are indicated. V

The figures illustrate the superimposed, intermeshing relationship of the two closed zippers. it will'be noted that on one side of the common center of the closed zippers the elements 6 and 14 alternate in their longitudinal positions while on the other side'the elements 8 and 16 similarly alternate. The meshing of the'tap'es in this fashion requires no special care since, whenthey are superimposed and generally pressed together, the elements will naturally fall in the intermeshed relationship due to the fact that their edges "are rounded. In providing such an assembly, thereforefitis not necessary to provide'any particular element locating devices such as geared wheels or the like,the"me repressing of the tapes together under tension sufiicing' to give rise to the desired relationship.

For the promotion of extremely reliable electrical com t in ui'ty, the condition illustrated in Figure 3 ts'ue'strably attained, the pairs of tapes being pressed together by suitable belts, rollers or the like or merely tensioned plates indicated at 22. The result, as is indicated in Figure 3, is to tilt the elements about their longitudinal center lines of contact to provide to some extent the co nditions which are described in my application Serial'No, 30l,S10, involvingthe tilting of the pyramidal projects 18' in the similar-sockets 20 promoting additional contactoyerand abovethat which issecured by the mere engagement of the zipper elements of the two closed sets.

Assemblies such as indicated in Figures 1 to 3 will be found to provide reliable electrical continuity along very considerable lengths of the zippers, so that if electrical connection to a current input terminal is provided at only a single point there is provided good current flow through a long extent of the assembly.

This condition is utilized in electrolytic treatment in the continuous type of method and apparatus illustrated in Figure 4. A supply reel 24 is illustrated as having a pair of closed zippers already assembled in the intermeshing relationship passing at 26 about the guide rollerZS located in the electrolytic tank 30. It will, of course, be evident that the zippers need not be preassembled on the supply reel, but that assembly 'may be secured asthey. pass from separate reels to a guide roller such as 28. From the tank '30 in which they are submerged in the electrolyte 31, the zippers pass about a second guide roller -32 and thence outof the tank, beingueeleduptogether as indicated at 34, or, if desired, being taken up on separate reels. Current is introduced to the zipper elements by a' suitable contact device such as a conductive roller 36 connected to one terminal 38 of the current supply. The other terminal 42 of the supply is electrically connected to the electrodes 45. Inthe case of electroplating, the terminal 38would be the cathode of a direct current supply, terminal lz beingthe anode. In the case of anodizing, the'electrical conditions would be reversed. It will be evident that in the case of anodizing with alternating current the connections illustrated in Figure 4 may be used but,'it will, in general, be more advantageous to provide current flow between a pair of the, zipper assemblies, one

- being connected to one terminal of the alternating supply and the other to the other terminal of the same supply. In any case, it will be evident that in a single tank there may be passed for treatment a large number ofzipper assemblies arranged electrically in parallel.

Belts 44 of rubber or the like are illustrated as providing the pressure devices on the ,fabric tapes corresponding to the elements 2; shown in Figure 3.

As "will be evident from the foregoing, the single region of contact provided for each zipper assembly 3 as at 36 suflices for current conduction for electrolytic action through the eztent of immersion of the zipper assernbly in the electrolyte 31.

'lhe particular treatment involved depends entirely upon the results desired and need not be detailed, reference beingrnade to the discussions of suitable baths, dye procedures and sealing procedures set forth in my patents mentioned above, any of vvhi ch are herein applicable. Astherein pointed out, when anodizing of aluminum zipper elements is being effected followed by dyeing, the cotton tapes may be si mult aneously dyed, or, alternatively, the cotton tapes may be predyed or subsequently dyed in contrasting colors or with different types of dyes even in substantially the same colors as the zipper elements.

Desirably, in a continuous anodizingprocess such as herein described there is used a type'of bath which will effecthnodizing in a minimum of time, utilizing high current densitiesjso' that the 'progressof'the' tapes may "bespeeded up consistently with "having each element subject to the anodizing action for a suflicient period to secure the desired thickness and type of coating. Sulfuric acid electrolytes are suitable for such anodizing, utilizing direct or alternating current. Numerous anodizing procedures of known types may be used and, consequently, need not be specifically de-. scribed.

The continuity of the anodized coating or plating will be interrupted at the sides of the assembled zippers which are in contact. This, however, is not generally of importance since each zipper will be finally used with a particular face exposed. In the case of electroplating, if complete coverage on both sides of the zipper is desired, it will be evident that the treatment may be repeated, bringing the opposite sides of the zippers into engagement. This, however, is not possible in the case of anodizing since the anodized coating is of an insulating nature.

While the method, as described above, is particularly adapted to a continuous electrolytic process, it will be evident that intermeshed zippers may be racked in various fashions, for example, Wound about suitable gridlike supports, or stretched between spaced mounting elements, or the like, to provide batch type of treatment.

What is claimed is:

1. A method of electrolytically treating slide fasteners of the zipper type having metallic interengaging elements secured to fabric tapes comprising supporting in an electrolytic bath four zipper tapes in the form of a pair of closed zippers by means engaging only the zipper tapes and not the elements secured thereto with the two closed zippers in flatwise engagement with each other and with the elements of one closed zipper intermeshing with the elements of the other closed zipper, positioning electrodes in the bath adjacent to the outwardly turned side of each of the closed zippers and spaced therefrom, and causing conductive engagement of at least one element of one of said closed zippers and of at most not more than a small portion of the number of elements immersed in the bath with a member carrying current for treatment.

2. A method of electrolytically treating slide fasteners of the zipper type having metallic interengaging elements secured to fabric tapes comprising progressing together in an electrolytic bath four zipper tapes in the form of a pair of closed zippers by moving means engaging only the zipper tapes and not the elements secured thereto with the two closed zippers in flatwise engagement with each other and with the elements of one closed zipper intermeshing with the elements of the other closed zipper, positioning electrodes in the bath adjacent to the outwardly turned side of each of the closed zippers and spaced therefrom, and causing conductive engagement of at least one element of one of said closed zippers and of at most not more than a small portion of the number of elements immersed in the bath with a member carrying current for treatment.

3. A method of electrolytically treating slide fasteners of the zipper type having metallic interengaging elements secured to fabric tapes comprising supporting in an electrolytic bath four zipper tapes in the form of a pair of closed zippers by means engaging only the zipper tapes and not the elements secured thereto with the two closed zippers in flatwise engagement with each other and with the elements of one closed zipper intermeshing with the elements of the other closed zipper and with the elements on opposite sides of the longitudinal center line of at least one of said closed zippers angularly flexed relatively to each other about said center line, positioning electrodes in the bath adjacent to the outwardly turned side of each of the closed zippers and spaced therefrom, and causing conductive engagement of at least one element of one of 6 said closed zippers and of at most not more than a small portion of the number of elements immersed in the bath with a member carrying current for treatment.

4. A method of electrolytically treating slide fasteners of the zipper type having metallic interengaging elements secured to fabric tapes comprising progressing together in an electrolytic bath four zipper tapes in the form of a pair of closed zippers by moving means engaging only the zipper tapes and not the elements secured thereto with the two closed zippers in flatwise engagement with each other and with the elements of one closed zipper intermeshing with the elements of the other closed zipper and with the elements on opposite sides of the longitudinal center line of at least one of said closed zippers angularly flexed relatively to each other about said center line, positioning electrodes in the bath adjacent to the outwardly turned side of each of the closed zippers and spaced therefrom, and causing conductive engagement of at least one element of one of said closed zippers and of at most not more than a small portion of the number of elements immersed in the bath with a member carrying current for treatment.

5. Apparatus for the electrolytic treatment of slide fasteners of the zipper type having metallic interengaging elements secured to fabric tapes comprising a tank containing an electrolyte, means engaging only the zipper tapes and not the elements securedthereto for supporting four zipper tapes in the form of a pair of closed zippers in the electrolyte within said tank with the two closed zippers in flatwise engagement with each other and with the elements of one closed zipper intermeshing with the elements of the other closed zipper, means providing an electrode in the bath adjacent to the outward- 1y turned side of each of the closed zippers and spaced therefrom, and means including a current carrying member conductively engaging at least one element of one of said zippers and at most not more than a small portion of the number of elements immersed in the bath.

6. Apparatus for the electrolytic treatment of slide fasteners of the zipper type having metallic interengaging elements secured to fabric tapes comprising a tank containing an electrolyte, means engaging only the zipper tapes and not the elements secured thereto for progressing together four zipper tapes in the form of a pair of closed zippers in the electrolyte within said tank with the two closed zippers in flatwise engagement with each other and with the elements of one closed zipper intermeshing with the elements of the other closed zipper, means providing an electrode in the bath adjacent to the outwardly turned side of each of the closed zippers and spaced therefrom, and means including a current carrying member conductively engaging at least one element of one of said zippers and at most not more than a small portion of the number of elements immersed in the bath.

References Cited in the file of this patent UNITED STATES PATENTS 1,970,459 Kelley Aug. 14, 1934 2,326,707 Thomas et a1 Aug. 10, 1943 2,334,054 Wooters Nov. 9, 1943 2,517,907 Mikulas Aug. 8, 1950 2,572,838 Cohn Oct. 30, 1951 2,591,042 Berman et a1. Apr. 1, 1952 FOREIGN PATENTS 715,118 Germany Dec. 15, 1941 929,854 France July 22,.1947 641,976 Great Britain Aug. 23, 1950 261,954 Switzerland Sept. 1, 1949 

1. A METHOD OF ELECTROLYTICALLY TREATING SLIDE FASTENERS OF THE ZIPPER TYPE HAVING METALLIC INTERENGAGING ELEMENTS SECURED TO FABRIC TAPES COMPRISING SUPPORTING IN AN ELECTROLYTIC BATH FOUR ZIPPER TAPES IN THE FORM OF A PAIR OF CLOSED ZIPPERS BY MEANS ENGAGING ONLY THE ZIPPER TAPES AND NOT THE ELEMENTS SECURED THERETO WITH THE TWO CLOSED ZIPPERS IN FLATWISE ENGAGEMENT WITH EACH OTHER WITH THE ELEMENTS OF ONE CLOSED ZIPPER INTERMESHING WITH THE ELEMENTS OF THE OTHER CLOSED ZIPPER POSITIONING ELECTRODES IN THE BATH ADJACENT TO THE OUTWARDLY TURNED SIDE OF EACH OF THE CLOSED ZIPPERS AND SPACED THEREFROM, AND CAUSING CONDUCTIVE ENGAGEMENT OF AT LEAST ONE ELEMENT OF ONE OF SAID CLOSED ZIPPERS AND OF AT MOST NOT MORE THAN A SMALL PORTION OF THE MEMBER OF ELEMENTS IMMERSED IN THE BATH WITH A MEMBER CARRYING CURRENT FOR TREATMENT. 